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Boulder researcher teams on study showing rapid Antarctica warming

NCAR climatologist fears greater contribution to rising sea level

By Charlie Brennan Camera Staff Writer

Posted:
12/23/2012 08:03:45 PM MST

Updated:
12/23/2012 08:04:03 PM MST

Researchers have discovered that the central region of the West Antarctic Ice Sheet is experiencing twice as much warming as previously thought. Their analysis of the temperature record from Byrd Station (indicated by a star) sheds some light on temperature changes over a broad portion of the ice sheet.
(Courtesy)

The West Antarctic Ice Sheet is showing nearly twice as much warming as previously thought, according to a new study co-authored by a researcher at the National Center for Atmospheric Research.

The discovery, published Sunday in the journal Nature Geoscience, raises additional concerns about the degree to which Antarctica will contribute to sea level rise.

"If this melt continues, if the summer warming continues, we could begin to see increased runoff from the West Antarctic Ice Sheet later in the century that could enhance its ongoing contribution to sea level rise," said Andy Monaghan, the NCAR climatologist who co-authored the study.

The research, which builds upon Monaghan's doctoral work at Ohio State University in 2008, was also co-authored by his doctoral advisor, OSU professor of geography David Bromwich, who is also a senior research scientist at the Byrd Polar Research Center.

"Our record suggests that continued summer warming in West Antarctica could upset the surface mass balance of the ice sheet, so that the region could make an even bigger contribution to sea level rise than it already does," Bromwich said in a news release.

Now, Monaghan said, the West Antarctic Ice Sheet contributes about 0.2 millimeters per year to global sea level rise, or about one-fifteenth of the 3 millimeters that the sea level rises each year.

Rising sea levels are a central concern for those monitoring climate change, due to the number of highly populated areas that have grown up in coastal zones around the planet. The east and west coasts of the United States are "particularly vulnerable" to sea level rise, Monaghan said.

The study shows warming trends occurring during the summer months of the Southern Hemisphere, December through February.

The temperature record from Byrd Station, an outpost in the center of the West Antarctic Ice Sheet, shows an increase of 4.3 degrees in average annual temperature from 1958. The rate of increase is three times faster than the average temperature increase around the planet for the same period of time.

"It's almost double what we previously thought, and it indicates the climate over West Antarctica has risen half a degree Celsius per decade" since 1958. "That's about 0.9 degrees Farenheit per decade."

Researchers have been unable in the past to make great use of readings from the Byrd Station, established in 1957, because of incomplete observations there, due to its not having been continuously inhabited.

A year-round automated station was put in place in 1980, but even that has been subject to frequent power outages, particularly during the extended polar night, when its solar panels are unable to recharge.

Monaghan and Bromwich previously reconstructed the Antarctic-wide temperature history over the last half-century using station records from around the continent, and published those results in 2008.

Now, the two researchers, working with partners at OSU and the University of Wisconsin-Madison, have completed the data gaps through use of a computer model of the atmosphere and a numerical analysis method.

"But even if you didn't in-fill it with the simulations, you still get these strong trends," Monaghan said. "It's really the observations telling us this. It's dangerous to overstate the simulated part of the record."

And, Bromwich said, "West Antarctica is one of the most rapidly changing regions on Earth, but it is also one of the least known. Our study underscores the need for a reliable network of meteorological observations throughout West Antarctica, so that we can know what is happening -- and why -- with more certainty."

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